Growth and reproductive post-fire responses of two shrubs in semiarid Patagonian grasslands

2015 ◽  
Vol 24 (6) ◽  
pp. 809 ◽  
Author(s):  
S. L. Gonzalez ◽  
L. Ghermandi ◽  
D. V. Peláez
Keyword(s):  
Plant Architecture ◽  
Fire Regime ◽  
Growing Season ◽  
Fire Intensity ◽  
High Survival ◽  
Fire Temperature ◽  
North West ◽  
Bud Position ◽  
Survival And Growth ◽  
In Fire

Variation in fire intensity affects the post-fire survival and growth of shrubs. We examined effects of maximum fire temperature (a proxy for fire intensity) on the survival, growth and reproductive performance of the shrubs Mulinum spinosum and Senecio bracteolatus at 1 and 2 years post-fire in north-west Patagonian grasslands. We applied two fire temperature treatments to plants of each species. All M. spinosum plants survived fire treatments but high fire temperature notably decreased survival of S. bracteolatus. Bud position and plant architecture probably influenced shrub survival. During the first growing season, M. spinosum did not produce seeds whereas S. bracteolatus plants burned at low temperature produced three times more seeds and bigger seeds than unburned plants. Also, seeds from burned plants of S. bracteolatus had higher germinability than seed from unburned plants. High survival and resprouting capacity of M. spinosum even after high fire intensity indicate that this species might be less affected by changes in fire regime.

scholarly journals An assessment of the implementation and outcomes of recent changes to fire management in the Kruger National Park

Koedoe ◽  
2008 ◽  
Vol 50 (1) ◽  
Author(s):  
Brian W. Van Wilgen ◽  
Navashni Govender ◽  
Sandra MacFadyen
Keyword(s):  
National Park ◽  
Fire Management ◽  
Fire Regime ◽  
Kruger National Park ◽  
Fire Intensity ◽  
Target Area ◽  
Large Fires ◽  
Sufficient Degree ◽  
Burnt Areas ◽  
In Fire

This paper reviews recent changes in fire management in the Kruger National Park, and assesses the resulting fire patterns against thresholds of potential concern. In 2002, a lightning-driven approach was replaced by an approach that combined point ignitions with unplanned and lightning fires. The approach aimed to burn an annual target area, determined by rainfall and fuel conditions, in point-ignition fires of different sizes. Most of the original fire-related thresholds of potential concern (TPCs) were incorporated into the new approach. The annual target area to be burnt ranged from 12 to 24% of the park between 2002 and 2006. The total area burnt generally exceeded the targets each year, and management fires accounted for less than half of the total area burnt. The fire regime was dominated by very large fires (> 5 000 ha) which accounted for 77% of the total area burnt. New TPCs were developed to assess whether the fire regime encompassed a sufficient degree of variability, in terms of fire intensity and the spatial distribution of burnt areas. After assessment and adjustment, it appears that these TPCs have not yet been exceeded. The point-ignition approach, and its evaluation in terms of variability and heterogeneity, is based on the untested assumption that a diverse fire regime will promote biodiversity. This assumption needs to be critically assessed. We recommend that the practice of point ignitions be continued, but that greater efforts be made to burn larger areas earlier in the season to reduce large and intense dry-season fires.

scholarly journals Plant responses to fire in a Mexican arid shrubland

Fire Ecology ◽  
2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Dante Arturo Rodríguez-Trejo ◽  
Juli G. Pausas ◽  
Andrés Gelacio Miranda-Moreno
Keyword(s):  
Fire Regime ◽  
Fire Severity ◽  
Survival Rates ◽  
Biosphere Reserve ◽  
Fire Intensity ◽  
Plant Responses ◽  
High Survival ◽  
Arid Environments ◽  
Probability Models ◽  
Fire Scar

Abstract Background Fire responses of species in arid environments have only been scarcely studied. We studied four species (Dasyliron lucidum Zucc., Juniperus deppeana Steud., Echinocactus platyacanthus Link & Otto, and Agave potatorum Zucc.) in the Tehuacán-Cuicatlán Biosphere Reserve, Mexico. The objectives were to describe and quantify survival and resprouting, as well as the factors determining them, for the selected species. Six months after a 330 ha wildfire in 2014, 32 plots were established on three transects. Forest dasometric and fire severity variables were recorded. Logistic regression was utilized to obtain mortality and resprouting probability models, as well as linear regression to detect relationships among post- and pre-fire variables. Results All species had high survival rates (74.5 to 97.7%). All surviving D. lucidum individuals resprouted apically. For J. deppeana, the probability of mortality was directly related to fire scar height on the trunk and inversely related to its diameter, whereas the probability of crown recovery was inversely related to the proportion of the tree height scorch. For E. platyacanthus, necrosed height was directly related to plant height. There was a positive relationship between basal area and the emission of new leaves for the A. potatorum. Conclusions In the different species, several traits that allowed high fire survival rates were observed (e.g., thick cortex or bark, fleshy non-flammable leaves, flammable leaves that reduce fire intensity, high volume to surface ratio). Many of these were primarily linked to drought resistance. All species gain fire resistance or tolerance as they increase in size. We concluded that the studied arid ecosystem of Mexico can withstand an altered or a base fire regime.

scholarly journals Distinguishing disturbance from perturbations in fire-prone ecosystems

2019 ◽  
Vol 28 (4) ◽  
pp. 282 ◽  
Author(s):  
Jon E. Keeley ◽  
Juli G. Pausas
Keyword(s):  
Fire Regime ◽  
Natural Disturbance ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Fire Intensity ◽  
Ecosystem Process ◽  
Type Conversion ◽  
Vegetation Shifts ◽  
In Fire ◽  
Historical Range

Fire is a necessary ecosystem process in many biomes and is best viewed as a natural disturbance that is beneficial to ecosystem functioning. However, increasingly, we are seeing human interference in fire regimes that alters the historical range of variability for most fire parameters and results in vegetation shifts. Such perturbations can affect all fire regime parameters. Here, we provide a brief overview of examples where anthropogenically driven changes in fire frequency, fire pattern, fuels consumed and fire intensity constitute perturbations that greatly disrupt natural disturbance cycles and put ecosystems on a different trajectory resulting in type conversion. These changes are not due to fire per se but rather anthropogenic perturbations in the natural disturbance regime.

scholarly journals Twenty-first century droughts have not increasingly exacerbated fire season severity in the Brazilian Amazon

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Libonati ◽  
J. M. C. Pereira ◽  
C. C. Da Camara ◽  
L. F. Peres ◽  
D. Oom ◽  
...  
Keyword(s):  
Forest Fires ◽  
Brazilian Amazon ◽  
First Century ◽  
Fire Season ◽  
Fire Intensity ◽  
Amazon Forest ◽  
Active Fire ◽  
Fire Activity ◽  
Twenty First Century ◽  
In Fire

AbstractBiomass burning in the Brazilian Amazon is modulated by climate factors, such as droughts, and by human factors, such as deforestation, and land management activities. The increase in forest fires during drought years has led to the hypothesis that fire activity decoupled from deforestation during the twenty-first century. However, assessment of the hypothesis relied on an incorrect active fire dataset, which led to an underestimation of the decreasing trend in fire activity and to an inflated rank for year 2015 in terms of active fire counts. The recent correction of that database warrants a reassessment of the relationships between deforestation and fire. Contrasting with earlier findings, we show that the exacerbating effect of drought on fire season severity did not increase from 2003 to 2015 and that the record-breaking dry conditions of 2015 had the least impact on fire season of all twenty-first century severe droughts. Overall, our results for the same period used in the study that originated the fire-deforestation decoupling hypothesis (2003–2015) show that decoupling was clearly weaker than initially proposed. Extension of the study period up to 2019, and novel analysis of trends in fire types and fire intensity strengthened this conclusion. Therefore, the role of deforestation as a driver of fire activity in the region should not be underestimated and must be taken into account when implementing measures to protect the Amazon forest.

scholarly journals Prescribed burning in a mediterranean-climate region mitigates the disturbance by bushfire to a critical food resource for an endangered bird, the Carnaby’s cockatoo

Fire Ecology ◽  
2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Valerie S. Densmore ◽  
Emma S. Clingan
Keyword(s):  
Seed Production ◽  
Prescribed Burning ◽  
Fire Regime ◽  
Fire Hazard ◽  
Food Resource ◽  
Management Tool ◽  
Fire Intensity ◽  
Prescribed Burns ◽  
Low Intensity ◽  
Percentage Survival

Abstract Background Prescribed burning is used to reduce fire hazard in highly flammable vegetation types, including Banksia L.f. woodland that occurs on the Swan Coastal Plain (SCP), Western Australia, Australia. The 2016 census recorded well over 1.9 million people living on the SCP, which also encompasses Perth, the fourth largest city in Australia. Banksia woodland is prone to frequent ignitions that can cause extensive bushfires that consume canopy-stored banksia seeds, a critical food resource for an endangered bird, the Carnaby’s cockatoo (Calyptorynchus latirostris, Carnaby 1948). The time needed for banksias to reach maturity and maximum seed production is several years longer than the typical interval between prescribed burns. We compared prescribed burns to bushfires and unburned sites at three locations in banksia woodland to determine whether low-intensity prescribed burns affect the number of adult banksias and their seed production. Study sites were matched to the same vegetation complex, fire regime, and time-since-fire to isolate fire intensity as a variable. Results Headfire rates of spread and differenced normalized burn ratios indicated that prescribed burning was generally of a much lower intensity than bushfire. The percentage survival of adult banksias and their production of cones and follicles (seeds) did not decrease during the first three years following a prescribed burn. However, survival and seed production were significantly diminished followed high-intensity bushfire. Thus, carrying capacity for Carnaby’s cockatoo was unchanged by prescribed burning but decreased markedly following bushfire in banksia woodland. Conclusions These results suggest that prescribed burning is markedly different from bushfire when considering appropriate fire intervals to conserve canopy habitats in fire-resilient vegetation communities. Therefore, low-intensity prescribed burning represents a viable management tool to reduce the frequency and extent of bushfire impacts on banksia woodland and Carnaby’s cockatoo.

Fire regime shift linked to increased forest density in a piñon–juniper savanna landscape

2014 ◽  
Vol 23 (2) ◽  
pp. 234 ◽  
Author(s):  
Ellis Q. Margolis
Keyword(s):  
Regime Shift ◽  
Fire History ◽  
Fire Regime ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Climatic Conditions ◽  
Tree Density ◽  
High Severity ◽  
Wide Range ◽  
In Fire

Piñon–juniper (PJ) fire regimes are generally characterised as infrequent high-severity. However, PJ ecosystems vary across a large geographic and bio-climatic range and little is known about one of the principal PJ functional types, PJ savannas. It is logical that (1) grass in PJ savannas could support frequent, low-severity fire and (2) exclusion of frequent fire could explain increased tree density in PJ savannas. To assess these hypotheses I used dendroecological methods to reconstruct fire history and forest structure in a PJ-dominated savanna. Evidence of high-severity fire was not observed. From 112 fire-scarred trees I reconstructed 87 fire years (1547–1899). Mean fire interval was 7.8 years for fires recorded at ≥2 sites. Tree establishment was negatively correlated with fire frequency (r=–0.74) and peak PJ establishment was synchronous with dry (unfavourable) conditions and a regime shift (decline) in fire frequency in the late 1800s. The collapse of the grass-fuelled, frequent, surface fire regime in this PJ savanna was likely the primary driver of current high tree density (mean=881treesha–1) that is >600% of the historical estimate. Variability in bio-climatic conditions likely drive variability in fire regimes across the wide range of PJ ecosystems.

Fire regime impacts on post-fire diurnal land surface temperature change over North American boreal forest

2021 ◽  
Author(s):  
Jie Zhao ◽  
Chao Yue ◽  
Philippe Ciais ◽  
Xin Hou ◽  
Qi Tian
Keyword(s):  
Climate Change ◽  
Regression Analysis ◽  
Land Surface ◽  
Fire Regime ◽  
Fire Severity ◽  
Linear Regression Analysis ◽  
Fire Regimes ◽  
Fire Intensity ◽  
Surface Temperature Change ◽  
One Year

<p>Wildfire is the most prevalent natural disturbance in the North American boreal (BNA) forest and can cause post-fire land surface temperature change (ΔLST<sub>fire</sub>) through biophysical processes. Fire regimes, such as fire severity, fire intensity and percentage of burned area (PBA), might affect ΔLST<sub>fire</sub> through their impacts on post-fire vegetation damage. However, the difference of the influence of different fire regimes on the ΔLST<sub>fire</sub> has not been quantified in previous studies, despite ongoing and projected changes in fire regimes in BNA in association with climate change. Here we employed satellite observations and a space-and-time approach to investigate diurnal ΔLST<sub>fire</sub> one year after fire across BNA. We further examined potential impacts of three fire regimes (i.e., fire intensity, fire severity and PBA) and latitude on ΔLST<sub>fire</sub> by simple linear regression analysis and multiple linear regression analysis in a stepwise manner. Our results demonstrated pronounced asymmetry in diurnal ΔLST<sub>fire</sub>, characterized by daytime warming in contrast to nighttime cooling over most BNA. Such diurnal ΔLST<sub>fire</sub> also exhibits a clear latitudinal pattern, with stronger daytime warming and nighttime cooling one year after fire in lower latitudes, whereas in high latitudes fire effects are almost neutral. Among the fire regimes, fire severity accounted for the most (43.65%) of the variation of daytime ΔLST<sub>fire</sub>, followed by PBA (11.6%) and fire intensity (8.5%). The latitude is an important factor affecting the influence of fire regimes on daytime ΔLST<sub>fire</sub>. The sensitivity of fire intensity and PBA impact on daytime ΔLST<sub>fire</sub> decreases with latitude. But only fire severity had a significant effect on nighttime ΔLST<sub>fire</sub> among three fire regimes. Our results highlight important fire regime impacts on daytime ΔLST<sub>fire</sub>, which might play a critical role in catalyzing future boreal climate change through positive feedbacks between fire regime and post-fire surface warming.</p>

scholarly journals Sensitivity of woody carbon stocks to bark investment strategy in Neotropical savannas and forests

2018 ◽  
Vol 15 (1) ◽  
pp. 233-243 ◽  
Author(s):  
Anna T. Trugman ◽  
David Medvigy ◽  
William A. Hoffmann ◽  
Adam F. A. Pellegrini
Keyword(s):  
Fire Regime ◽  
Investment Strategy ◽  
Fire Frequency ◽  
Carbon Stocks ◽  
Plant Functional Groups ◽  
High Survival ◽  
Survival Strategy ◽  
Aboveground Carbon ◽  
Large Trees ◽  
Neotropical Savannas

Abstract. Fire frequencies are changing in Neotropical savannas and forests as a result of forest fragmentation and increasing drought. Such changes in fire regime and climate are hypothesized to destabilize tropical carbon storage, but there has been little consideration of the widespread variability in tree fire tolerance strategies. To test how aboveground carbon stocks change with fire frequency and composition of plants with different fire tolerance strategies, we update the Ecosystem Demography model 2 (ED2) with (i) a fire survivorship module based on tree bark thickness (a key fire-tolerance trait across woody plants in savannas and forests), and (ii) plant functional types representative of trees in the region. With these updates, the model is better able to predict how fire frequency affects population demography and aboveground woody carbon. Simulations illustrate that the high survival rate of thick-barked, large trees reduces carbon losses with increasing fire frequency, with high investment in bark being particularly important in reducing losses in the wettest sites. Additionally, in landscapes that frequently burn, bark investment can broaden the range of climate and fire conditions under which savannas occur by reducing the range of conditions leading to either complete tree loss or complete grass loss. These results highlight that tropical vegetation dynamics depend not only on rainfall and changing fire frequencies but also on tree fire survival strategy. Further, our results indicate that fire survival strategy is fundamentally important in regulating tree size demography in ecosystems exposed to fire, which increases the preservation of aboveground carbon stocks and the coexistence of different plant functional groups.

Developing an Adaptive Management approach to prescribed burning: a long-term heathland conservation experiment in north-west Italy

2009 ◽  
Vol 18 (6) ◽  
pp. 727 ◽  
Author(s):  
Davide Ascoli ◽  
Rachele Beghin ◽  
Riccardo Ceccato ◽  
Alessandra Gorlier ◽  
Giampiero Lombardi ◽  
...  
Keyword(s):  
Experimental Design ◽  
Adaptive Management ◽  
Prescribed Burning ◽  
Fire Regime ◽  
Management Approach ◽  
Detailed Measurement ◽  
Research Issues ◽  
North West ◽  
Heathland Management

Calluna vulgaris-dominated heathlands are globally important habitats and extremely scarce outside of north-west Europe. Rotational fire, grazing and cutting by local farmers were dominant features of past heathland management throughout Europe but have been abandoned, altering the historical fire regime and habitat structure. We briefly review research on Calluna heathland conservation management and provide the background and methodology for a long-term research project that will be used to define prescribed fire regimes in combination with grazing and cutting, for management of Calluna heathlands in north-west Italy. We outline the ecological and research issues that drive the fire experiment, making explicit the experimental design and the hypotheses that will be tested. We demonstrate how Adaptive Management can be used to inform decisions about the nature of fire prescriptions where little formal knowledge exists. Experimental plots ranging from 600 to 2500 m2 are treated according to one of eight alternative treatments (various combinations of fire, grazing and cutting), each replicated four times. To date, all treatments have been applied for 4 years, from 2005 to 2008, and a continuation is planned. Detailed measurement of fire characteristics is made to help interpret ecological responses at a microplot scale. The results of the experiment will be fed back into the experimental design and used to inform heathland management practice in north-west Italy.

scholarly journals Historical fire records at the two ends of Iberian Central Mountain System: Estrela massif and Ayllón massif

2019 ◽  
pp. 31
Author(s):  
Catarina Romão Sequeira ◽  
Cristina Montiel-Molina ◽  
Francisco Castro Rego
Keyword(s):  
Fire Regime ◽  
Fire Regimes ◽  
Historical Record ◽  
Multiscale Approach ◽  
Natural Region ◽  
Fire Use ◽  
Prone Area ◽  
Mountain System ◽  
History Of ◽  
In Fire

The Iberian Peninsula has a long history of fire, as the Central Mountain System, from the Estrela massif in Portugal to the Ayllón massif in Spain, is a major fire-prone area. Despite being part of the same natural region, there are different environmental, political and socio-economic contexts at either end, which might have led to distinct human causes of wildfires and associated fire regimes. The hypothesis for this research lies in the historical long-term relationship between wildfire risks and fire use practices within a context of landscape dynamics. In addition to conducting an analysis of the statistical period, a spatial and temporal multiscale approach was taken by reconstructing the historical record of prestatistical fires and land management history at both ends of the Central Mountain System. The main result is the different structural causes of wildland fires at either end of the Central Mountain System, with human factors being more important than environmental factors in determining the fire regimes in both contexts. The study shows that the development of the fire regime was non-linear in the nineteenth and twentieth centuries, due to broader local human context factors which led to a shift in fire-use practices.

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